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Abstract
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In this paper, in the framework of massive bigravity, we study all possible cosmic evolutions by using a
method in which the modified Friedmann equation is written in a form in which the scale factor evolves like
the motion of a particle under a “potential.” Massive bigravity provides this potential with the most general
mass interaction term, which can create new circumstances to find different kinds of cosmological
evolutions in the early Universe.We classify all possible cosmic evolutions according to the classifications
of the energy density as dust, radiation, and dust with phantom. The oscillating universe and Einstein static
state that exist initially may show a useful property of the early Universe, obtained in this model, in which
the initial singularity is avoided. The bouncing universe extracted in the massive bigravity model can
present a reasonable cosmic evolutionary behavior having a big bang initial point with the expansion phase
and switching to the contraction phase, leading to a final big crunch point. The large-valued graviton mass
m in the early times causes a very small aS (the Einstein static state scale factor), and λ ¼ ρ0a30
is a constant
parameter constructed of the present-day energy density and scale factor.
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